2148781781 has 2 divisors, whose sum is σ = 2148781782. Its totient is φ = 2148781780.

The previous prime is 2148781753. The next prime is 2148781783. The reversal of 2148781781 is 1871878412.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 2144616100 + 4165681 = 46310^2 + 2041^2 .

It is a cyclic number.

It is not a de Polignac number, because 2148781781 - 2⁶ = 2148781717 is a prime.

It is a super-2 number, since 2×2148781781² = 9234526284715063922, which contains 22 as substring.

Together with 2148781783, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (2148781783) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1074390890 + 1074390891.

It is an arithmetic number, because the mean of its divisors is an integer number (1074390891).

Almost surely, 2^2148781781 is an apocalyptic number.

It is an amenable number.

2148781781 is a deficient number, since it is larger than the sum of its proper divisors (1).

2148781781 is an equidigital number, since it uses as much as digits as its factorization.

2148781781 is an evil number, because the sum of its binary digits is even.

The product of its digits is 200704, while the sum is 47.

The square root of 2148781781 is about 46354.9542228228. The cubic root of 2148781781 is about 1290.4190656196.

The spelling of 2148781781 in words is "two billion, one hundred forty-eight million, seven hundred eighty-one thousand, seven hundred eighty-one".